class User():
    def __init__(self,first_name,last_name):
        self.first_name = first_name
        self.last_name = last_name
    def describe_user(self):
        print("user information: "+self.last_name+" "+self.first_name)
    def greet_uesr(self):
        print("hello "+self.last_name+" "+self.first_name)
user = User('huan','li')
user_1 = User('jie','xie')
user_2 = User('cai','xiao')
user.describe_user()
user.greet_uesr()
user_1.describe_user()
user_1.greet_uesr()
user_2.describe_user()
user_2.greet_uesr()